Power-operated forging tongs



May 29, 1962 T. ZIMMERMANN ETAL 3,036,854

POWER-OPERATED FORGING TONGS Filed March 21, 1956 s Sheets-Sheet 1 May 29, 1962 T. ZIMMERMANN ETAL 3,036,854

POWER-OPERATED FORGING TONGS 3 Sheets-Sheet 2 Filed March 21, 1956 Filed March 21, 1956 May 29, 1962 T. ZIMMERMANN ETAL 3,036,854

POWER-OPERATED FORGING TONGS 3 SheetsSheet 3 3,36,854 Patented May 29, 1962 3,036,854 POWER-OPERATED FORGWG TONGS Theo Zimmermann and Alois Ullrich, Siegen, Germany,

assignors to Dango & Dienenthal K.G., Siegen, Westphalia, Germany Filed Mar. 21, 1956, Ser. No. 572,954 4 Claims. (Ci. 2%88) In forging discs, rings and cubes, frequent turning of the forging is requisite in order to bring all surfaces under the hammer or between press jaws in turn. Up to now such .turning of the forging was usually accomplished by hand- Operated, chain-supported tongs or levers. However, work-manipulators have sometimes been employed for this purpose. These consisted of tongs whose jaws were equipped with blunt, round-nosed inserts. In forging the periphery of a disc or ring the jaws were first clamped near the outer edge of the work. If one wished to turn the forging on the anvil it was necessary to elevate the tongs; the work would then be revolved by its own weight as it swiveled the forging around the contact points of the jaws. With such a forging-manipulator the requisite movements can only be comparatively slow and must be accomplished with the expenditure of a great deal of physical effort by the operator as the great weight of the lift frame must always be raised and lowered at the same time. Furthermore, by this means the work can be rotated only in one direction, i.e. around its horizontal axis, so that a disc or ring, for example, could be forged only around its periphery.

This invention consists of a pair of power-driven swiveling tongs particularly adapted to forging-manipulators, for the forging of round discs, rings, cubes, etc. It avoids the disadvantages mentioned above and creates a pair or tongs of little dead weight that can be swiveled by manipulating these gripping arms in order to accomplish the desired movement of the forging they hold, including rotation around a vertical axis as well as a horizontal one. In this way the sides of discs and rings may be shaped as well as the periphery. According to the invention the tongs are swingably mounted in a forked carrier, its axis being parallel to the closing direction of the jaw-activating lever arms. An auxiliary power drive to swing the tongs will be found advantageous.

It is particularly desirable to connect the lever arms and the shaft on which they swing with the front ends of two tong jaws so that they will open and close with the tong jaws, regardless of position. A further advantage of this mode of construction is that the grip arms with their shaft could be interchangeable with the tong jaws so that the manipulator could also be used for draw-forging.

Connection between the lever arms and the actuating tong jaws can also be accomplished with ball joints. However, since the forging of heavy pieces requires extreme accuracy in the guiding of the levers to avoid unwanted canting of the forging, it is advisable to provide each lever arm with a swingable pressure block which in turn is mounted swingably and swiveling but unshiftingly on its respective tong jaw while both pressure blocks can he slid along on a common shaft.

Construction of the tongs as described above has the further advantage, as previously intimated, of permitting a disc or ring to be turned on a vertical axis, a requirement in forging the sides of rings and discs. According to this invention, turning on a vertical axis results if the disc or ring, lying flat on the anvil, is held against a firm guide during the lateral swinging operation of the grip arms.

The dew'ce according to the invention will now be more fully described with reference to the accompanying drawing, but it should be understood that the same is given by way of illustration and not of limitation and that many changes in the details may be made without departing from the spirit of the invention.

In the drawing:

FIG. 1 shows a general view of tongs according to the invention designed for use with a forging-manipulator;

FIG. 2 shows a longitudinal section of the tongs of FIG. 1;

FIG. 3 shows a section of FIG. 1 taken on section line IIIIII;

FIG. 4 shows a section of FIG. 2 taken on section line ,IV-IV;

FIG. 5 shows the manipulator in the operation of turning -a disc about a horizontal axis;

FIG. 6 shows the manipulator in turning the disc about a vertical axis;

FIG. 7 shows plan of the manipulator according to FIG. 6; and

FIG. 8 shows the manipulator tongs with a stop gauge attached.

FIGS. 14 show a support 1 with a carrier 2 mounted on a rotatable bearing. Mounted on carrier 2 by means of two shafts 3 are two jaw levers 4. By means of two toggle links 5 and the draw bar 6 these may be actuated hydraulically in conventional manner. The right-hand ends of the two jaw levers 4 are provided with bearing blocks that can turn and rock at the same time but cannot shift. Two pressure sleeves or blocks 7 are mounted on rotatable rings 8 which in turn are mounted on bearing pins or pivots 9 in the forked ends of the jaw levers 4. Each pressure block or sleeve 7 supports a gripping jaw 11 hinged respectively on the two bearing pins or pivots 10. The two gripping jaws 11 are hinged together at the left by bearing pin or pivot 12, the latter being longer than the combined thickness of the two grip arms so that its projecting ends act as guides in the slots of the guide body 13, the latter being fastened to shaft 14 which also passes through bearing holes 15 in the two pressure sleeves or blocks 7.

Guide body 13 is provided with an extension 16 which is linked to a longitudinally sliding sleeve 18, on carrier 2, by means of rod 17. A ring 19 has a running fit in a recess in sleeve 18. Ring 19- does not turn with carrier 2, being prevented therefrom by the stationary guide 20 which engages a key slot or groove in the outside of ring 19. Ring 19 is further provided with link ears opposed at which are connected to two rods21 of two hydraulic pistons 21a. The two hydraulic cylinders 22 are mounted on support 1.

The operation of the tongs is as follows: in order to clamp a forging between the gripping jaws 11 the hydraulic drive of the manipulator tongs is switched on. By means of the draw rod 6 the two toggle links 5 are drawn back, thereby closing jaw levers 4. Since the righthand ends of the two jaw levers 4 engage the gripping jaws 11 through the pressure blocks 7 and guide shaft 14, the gripping jaws 11 also close as they turn on hinge bolts 12, thereby clamping the work between the inserts in the righthand end of each of the gripping jaws 11. Closing of gripping jaws 11 is accompanied by a displacement of the pressure blocks 7 along the shaft 14, and by a backward movement of hinge bolt 12 in the slots of guide body 13. Should it be desired to turn the clamped forging, the two hydraulic cylinders 22 are put under pressure. This results in displacement of ring 19 by means of piston rods 21. Movement of ring 19 carries with it the sleeve 18 and by means of draw rods 17, acting upon extension 16,

swings guide body 13 around guide shaft 14. Since the gripping jaws 22 are guided by slide 13 through hinge bolt 12, they partake of the swivel motion of the slide 13 about shaft 14. Gripping jaws 11 are thereby tilted so that the forging held between clamp inserts may be turned as desired.

By means of a mechanism not shown in the drawing, carrier 2 in the support 1 of the manipulator can be turned on its longitudinal axis. In this way the tongs may be turned and located as desired for forging either the periphery or the sides of a disc or ring within a range of 90. The sleeve 18 turns with the carrier 2 and the tongs, but ring 19 is held in position by guide 20. By means of hydraulic cylinders 22 any desired tilting of grip arms can be effected regardless of the radial position of tongs.

In opening the tongs, the hydraulic drive moves draw rod 6 to the right, thus returning the toggle links to their original position as shown in FIG. 1. Jaw levers 4, through pressure blocks 7, again carry with them the gripping jaws 11 and so open the tongs.

FIG. 5 shows the tong setting in forging the periphery of a disc. Guide shaft 14 is in horizontal position, and when gripping jaws 11 are tilted upwards the disc will swivel clockwise by its own weight.

FIG. 6 shows the tongs offset by 90 from their position of FIG. 5 and a fiat side of the disc resting on anvil 23. If gripping jaws 11 are swung as indicated by dotted lines in FIG. 7, the disc will assume a rotary motion against a stop 24 fastened to the press while its fiat side is being forged.

As shown in FIG. 8 a stop 25 may also be secured to the gripping jaws themselves.

What we claim is:

1. A gripping device adapted for use in forging work, comprising a carrier adapted to be mounted on a manipulator, a pair of levers pivotally mounted on said carrier for rotation in a first plane, link means engaging said levers for swinging them toward and away from each other in said first plane, a pair of universal joints respectively secured to said levers, a pair of gripping jaws respectively connected by said joints with said levers for entrainment thereby upon the swinging of said levers in said plane, said joints having a common axis, guide means for said jaws on said carrier swingable about said axis in a second plane perpendicular to said first plane, and operating means linked with said guide means for imparting to said guide means and concurrently therewith to said jaws a swinging motion in said second plane.

2. gripping device adapted for use in forging work, comprising a carrier adapted to be mounted on a manipulator, a pair of levers pivotally mounted on said carrier for rotation about respective fulcra in a first plane, link means engaging said levers for swinging them toward and away from each other in said first plane, a pair of universal joints respectively secured to said levers, a pair of gripping jaws respectively connected by said joints with said levers for entrainment thereby upon the swinging of said levers in said plane, said joints having a common axis, pivot means interconnecting said jaws at a third fulcrum, guide means for said jaws on said carrier swingable about said axis in a second plane perpendicular to said first plane, said guide means being slidably engaged by said pivot means, and operating means linked with said guide means for imparting to said guide means and concurrently therewith to said jaws a swinging motion in said second plane.

3. A gripping device adapted for use in forging work, comprising a carrier adapted to be mounted on a manipulator, a pair of levers pivotally mounted on said carrier for rotation about respective fulcra in a first plane, link means engaging said levers for swinging them toward and away from each other in said first plane, a pair of universal joints respectively secured to said levers, a pair of gripping jaws respectively connected by said joints with said levers for entrainment thereby upon the swinging of said levers in said plane, said joints being provided with a common shaft passing between said jaws, pivot means intetrconnecting said jaws at a third fulcrum, guide means for said jaws on said carrier swingable about said shaft in a second plane perpendicular to said first plane, said guide means being slidably engaged by said pivot means, and operating means linked with said guide means for imparting to said guide means and concurrently therewith to said jaws a swinging motion in said second plane.

4. A gripping device adapted for use in forging work, comprising a support adapted to be mounted on a manipulator, an elongated carrier rotatable about its axis on said support, a pair of levers pivotally mounted on said carrier for rotation about respective fulcra in a first plane containing said axis, link means engaging said levers for swinging them toward and away from each other in said first plane, a pair of universal joints respectively secured to said levers, a pair of gripping jaws respectively connected by said joints with said levers for entrainment thereby upon the swinging of said levers in said plane, said joints being provided with a common shaft passing between said jaws, pivot means interconnecting said jaws at a third fulcrum, guide means for said jaws on said carrier swingable about said shaft in a second plane perpendicular to said first plane, said guide means being slidably engaged by said pivot means, and hydraulic operating means on said support linked with said guide means for imparting to said guide means and concurrently therewith to said jaws a swinging motion in said second plane.

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